This invention concerns cooling systems for an automotive internal combustion engine and, more particularly, relates to an improved liquid coolant flow control assembly that incorporates a thermostat for controlling the flow of coolant between the internal combustion engine and the radiator and also controls the flow of coolant through the engine bypass passage.
There are two standard design arrangements for the location of the thermostat in an internal combustion engine for sensing the temperature of the coolant and preventing the coolant from flowing through the radiator. One is referred to as an outlet side thermostat design and the other is an inlet side thermostat design. In the outlet side design, the thermostat is located in the engine outside of the coolant circuit and it serves to control the temperature of the engine cooling system based on the temperature of the coolant exiting the engine. One advantage of this type of arrangement is that it allows for higher pump inlet pressures to avoid cavitation and offers lower radiator pressures for the cooling system. However, one problem with the outlet side design is that the engine can incur fluctuating coolant temperatures, which could lead to higher engine out emissions.
The inlet side thermostat design is located in the coolant inlet side of the engine cooling system and controls the temperature of the coolant based upon the temperature of the coolant flowing through the engine bypass, heater core return, and the radiator outlet. This form of thermostat arrangement has been found to better control the warm-up temperature, tends to reduce any thermal shock, and improves the emissions and fuel economy of the engine.
The present invention is intended to be incorporated into the cooling system of an internal combustion engine having the inlet side thermostat design. However, as will be apparent from the detailed description which follows, the present invention could be utilized with an engine cooling system having the outlet side thermostat design and provide similar advantages experienced by an engine having the inlet side thermostat design. More specifically, the present invention provides a cooling system for an internal combustion engine having a liquid coolant circuit for connecting the engine with a heater core and a radiator. The engine is provided with a fluid pump for pumping the liquid coolant through the liquid coolant circuit. In addition, a coolant flow control assembly forms a part of the liquid coolant circuit and is incorporated within a housing forming a part of the engine. A thermostat is located within the housing of the flow control assembly for controlling liquid coolant flow between the internal combustion engine and the radiator through the liquid coolant circuit. The housing, containing the coolant flow control assembly, is formed with a heater core inlet passage, a heater core bypass passage, an intake passage receiving liquid coolant from the radiator, and an outlet passage connected to the fluid pump. The thermostat has a valve member adapted to close the radiator intake passage when the liquid coolant is below a predetermined temperature. A heat responsive expandable and contractible medium is enclosed within a cylindrical body portion of the thermostat and serves to cause the valve member to move to an open position when the temperature of the liquid coolant is above the aforementioned predetermined temperature to allow liquid coolant to flow from the internal combustion engine into and through the radiator. In addition, the housing has a tapered counterbore within the bypass passage for receiving and enclosing the lower section of the thermostat""s cylindrical body within the tapered bore when the thermostat is in the open position so as to allow the heat responsive medium within such lower section to more effectively sense the temperature of the liquid coolant while controlling the flow of the liquid coolant through the bypass passage. The lower section and the tapered counterbore cooperate to provide a cleaning action within the bypass passage to prevent foreign debris from lodging within bypass passage.
Accordingly, one object of the present invention is to provide a new and improved cooling system for an internal combustion engine that incorporates a coolant flow control assembly having a thermostat which utilizes the enclosure of its heat responsive medium to control the size of the opening of the bypass passage.
Another object of the present invention is to provide a new and improved cooling system for an internal combustion engine that includes a flow control assembly having a housing formed with a heater core inlet passage, a heater core bypass passage, an intake passage receiving coolant from the radiator, and an outlet passage connected to the coolant pump and in which the flow control assembly is characterized in that the pellet enclosed body portion of the thermostat cooperates with a tapered opening formed in the bypass passage for effectively controlling the flow of the liquid coolant through the bypass passage.
A further object of the present invention is to provide a new and improved cooling system for an internal combustion engine that includes a flow control assembly having a housing formed with a heater core inlet passage a heater core bypass passage, an intake passage receiving coolant from the radiator, and an outlet passage connected to the coolant pump and in which the flow control assembly is characterized by having a thermostat which cooperates with a counterbore formed in the bypass passage for continuously allowing the flow of the liquid coolant through the bypass passage so as to prevent foreign debris such as core sand from lodging within the bypass passage when the thermostat is in the open position.
A still further object of the present invention is to provide a new and improved flow control assembly for the cooling system of an internal combustion engine in which the flow control assembly has a housing formed with a heater core inlet passage a heater core bypass passage, an intake passage receiving coolant from the radiator, an outlet passage connected to the coolant pump, and a thermostat having a valve member adapted to move between an open position and a closed position so as to control the flow of liquid coolant through the radiator and, at the same time, control the flow of the coolant through the bypass passage by causing a cylindrical section of the thermostat that contains a heat responsive medium to move into a tapered counterbore formed in the bypass passage when the valve member moves to its open position.